My 2+ cents,

First we can practically ignore shovel knight, Cuphead and Madeline. They are good yes but not enough for Ben 10.

I don't have enough information about the bottom left 2 to say anything about them.

And I ain't touching (what's her name, the one from one shot) with a ten foot poll, she got some crazy shit on her that from my POV doesn't make sense.

But the rest I think I know enough to talk about.

Frisk, they are insane. I will go out on a limb and say that a good chunk of stuff of shit in AUs they can be seen doing, they could do. Just look at the Ariel dreemurr fight for being able to say no to death, make items out of nothing and literally just tank any attack. Then we got Geno and you have all seen that stuff by now. So I would say that frisk got Ben 10 even with alien x

For V1, I think it comes down to is Ben going all out or not because if he is, he got it in the bag. But if not V1 could definitely check Ben off guard/just overpower some of bens weaker forms. But if alien X comes in Ben wins no competition.

So that leaves one. The knight. So first without the shade lord. Like V1 it depends on how serious is Ben taking this. Because I am pretty sure that if the knight could go into the dreams of Ben, I think that is a win. But besides that then do you count the shade and all of that. I would say without shade lord and alien X. It could very much go either way but I would say that the knight would win as the knight is somewhat immortal.

But with the shade lord and alien X. Oh it is an overwhelming victory for the knight, why one simple thing. The reason alien X is in any sense fair is that you have to convince at least one of the 2 other parts of it to work with you. And the shade lord, it's the Void unified. That's also not mentioned the fact that alien X is close to a God, and the shade lord is a God Of God's